Nghiên cứu mức độ ô nhiễm và đánh giá rủi ro phơi nhiễm các hợp chất erfluoroalkyl pfos và pfoa trong cá ở Việt Nam
Scientific Research Assessment of contamination levels and exposure risk of perfluoroalkyl substances (PFOS and PFOA) in Vietnamese fish Tran Thi Lieu1, Hoang Quoc Anh2, Nguyen Thi Anh Huong2, Tu Minh Nhat3, Nguyen Trong Nghia4, Nguyen Thi Chuc4, Nguyen Thi Quynh Hoa4*, Le Huu Tuyen2† Viet Nam National Institute of Occupational Safety and Health, Hanoi, Vietnam University of Science, Vietnam National University, Hanoi, Vietnam University of Science and Technology of Hanoi (USTH), Hanoi, Vietnam Faculty of Chemical Technology and Environment, Hung Yen University of Technology and Education, Hung Yen, Vietnam (Received: 16/06/2022; Accepted: 25/07/2022) Abstract Contamination levels of two typical perfluoroalkyl substances (PFASs) including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were evaluated in Vietnamese fish samples by using our monitoring results and database reported in previous studies In freshwater fish taken from West and Yen So Lakes (Hanoi), PFOS and PFOA concentrations ranged from < 0.030 to 0.48 (mean 0.12) ng/g, and from < 0.010 to 0.19 (mean 0.058) ng/g, respectively These levels were comparable to those measured in fish samples from other areas in Vietnam, but were generally lower than values documented for fish samples from other countries PFOS and PFOA daily intake doses via fish consumption ranged from 0.015 to 0.48 (mean 0.12) and from 0.005 to 0.20 (mean 0.065) ng/kg/day In general, these intake doses were lower than the reference dose of 20 ng/kg/day, suggesting acceptable levels of risk Keywords: PFOS, PFOA, fish, dietary exposure, Vietnam INTRODUCTION Perfloroalkyl substances (PFASs) such as perfluorocarboxylic acid (PFCAs) and perfluoroalkyl sulfonic acid (PFSAs) are persistent organic pollutants (POPs) with critical properties such as persistent in the environment, bioaccumulative, and toxic [1] Among PFASs, perfluorooctane sulfonic acid (PFOS) and related compounds were restricted by the Stockholm Convention on POPs in 2009 Perfluorooctanoic acid (PFOA) and related compounds were listed as eliminated chemicals by the Stockholm Convention in 2019 * † Co-corresponding author: Tel: +84 983713427 Corresponding author: Tel: +84 936577566 Email: hoameo2011@gmail.com Email: lehuutuyen@hus.edu.vn Vietnam Journal of Food Control - vol 5, no 4, 2022 658 Assessment of contamination levels and exposure risk of perfluoroalkyl substances … Structural formulas of PFOS and PFOA are shown in Figure These substances are persistent with excellent surface characteristics Therefore, they are popularly used in industries as additives in coating materials, paints, surfactants, textiles, foams, and emulsifiers [2] The contamination of PFASs in the environment and their occurrence in humans and animals have been reported since the 2000s [3-4] Because of PFAS abundance in water environment, many studies on the accumulation of PFASs in aquatic animals have been conducted for pollution monitoring and risk assessment purposes [5] Figure Structural formulas of PFOS and PFOA Little is known about the contamination and impacts of PFASs in Vietnam PFOS and PFOA were found for the first time in some water samples collected from Nhue River, Hanoi in 2006 at levels smaller than and 10 ng/L [6] Since then, PFASs have been detected in different sample matrices such as water, sediment, biota, human blood, breast milk, etc [79] Studies on PFAS in Vietnamese fish samples are scarce [7, 9] Moreover, these studies did not focus on evaluating PFAS exposure risks through fish consumption To assess contamination degree, human exposure, and health risks related to PFOS and PFOA, freshwater fish samples from West and Yen So Lakes (Hanoi) were examined for PFOS and PFOA concentrations in muscle tissues The results of this study were analyzed and compared with previous studies to provide comprehensive and updated information about PFOS and PFOA in Vietnamese fish Exposure levels and potential effects of these two compounds in fish were estimated through daily intake doses in the comparison with reference doses MATERIALS AND METHODS 2.1 Sample information Fish samples were collected by using nets in Yen So and West Lakes on June 2016 In each lake, individual samples of species were selected for PFOS and PFOA analysis (total n = 24) Investigated species include bighead carp (Hypophthalmichthys nobilis), common carp (Cyprinus carpio), rohu (Labeo rohita), and tilapia (Tilapia spp.) Data on PFOS and PFOA concentrations in fish samples from previous studies were also included to facilitate comparison Murakami et al (2011) reported PFOS and PFOA levels in snakehead samples collected from Bac Ninh and Hung Yen Provinces in 2007 [7] Lam et Vietnam Journal of Food Control - vol 5, no 4, 2022 659 Tran Thi Lieu, Hoang Quoc Anh, Nguyen Thi Anh Huong, … Le Huu Tuyen al (2017) analyzed PFOS and PFOA in species including tilapia (Oreochrommic niloticus, n = 10), snakehead (Chana striata, n = 3), dusky sleeper (Eleotris fusca, n = 3), shark catfish (Pangasius elongatus, n = 10), and flying barb (Esomus danricus, n = 5) collected between 2013 and 2015 from Da Rang (Phu Yen Province), Dong Nai River and Me Kong River [8] 2.2 Analytical methods The analytical method for PFOS and PFOA in fish samples was referred to previous studies [4, 8] The fish samples were stored at - 22 °C until analysis About g of muscle tissue was transferred to a 50-mL tube and homogenized with mL pure water by a T-25 Digital ULTRA-TURRAX® equipment (IKA, Germany) Then, one portion of homogenate (1 mL) was transferred into a new tube with surrogate standard, 0.5 M tetrabutylammonium hydrogen sulfate solution (1 mL), and 0.25 M sodium carbonate buffer solution (2 mL) The extraction process was conducted twice with × mL methyl tert-butyl ether on a KS 501 Digital shaker (IKA, Germany) Extract portions were pooled, evaporated, and redissolved in methanol (1 mL) before analysis The analytical standard (PFAC-MXB) containing PFOS and PFOA, and surrogate standard (MPFAC-MXA) containing 13C4-PFOA and 13C4-PFOS, were purchased from Wellington Laboratories The standard solutions were prepared in methanol One hundred microliters of the surrogate standard (13C4-PFOA and 13C4-PFOS) at a concentration of 10 ng/mL each compound was spiked into each sample The standard solutions for the calibration curve were prepared with PFOA and PFOS concentrations ranging from 0.1 to 20 ng/mL, with 13C4-PFOA and 13C4-PFOS as 10 ng/mL PFOS and PFOA were analyzed by using a liquid chromatography-mass spectrometry system (LCMS-8040, Shimadzu Corporation, Japan) The separation column and guard column were Poroshell 120 EC-C18 (inner diameter 2.1 mm, particle size 2.7 μm, length 150 mm and mm) The oven temperature was 40 °C Mobile phase comprised of channel A (methanol/ammonium acetate mmol/L, : 9, v/v), channel B (methanol), ratio of channel B: 50% (2.01 min), 95% (18 min), 95% (22 min), 50% (22.1 to 25 min) The flow rate of mobile phase was 0.25 mL/min Negative electron spray ionization (ESI–) and multireaction monitoring (MRM) modes were applied The MS parameters for PFOS were: m/z = 498.8 → 98.9; Q1 = 18 V; CE = 44 eV; Q3 = 17 V The MS parameters for PFOA were: m/z = 412.8 → 368.8; Q1 = 15 V; CE = 11 eV; Q3 = 24 V Concentrations of PFOS and PFOA in fish samples were calculated by internal standard/isotope dilution method and expressed in ng/g wet weight (w/w) Method detection limits (MDL) of PFOA and PFOS were 0.01 and 0.03 ng/g, respectively, which were estimated as the average blank level plus three times of blank standard deviation Method quantification limits (MQL) of PFOA and PFOS were 0.03 and 0.09 ng/g, respectively Calibration curves of PFOA and PFOS had correlation coefficients over 0.999, showing good linearity over the concentration range of 0.1 to 20 ng/mL Recoveries of PFOA and PFOS in matrix-spike samples (n = 3) at a spiking level of ng/g were 108 ± 7% and 97 ± 12% (RSD < 20%), indicating good accuracy and precision of our analytical method 660 Vietnam Journal of Food Control - vol 5, no 4, 2022 Assessment of contamination levels and exposure risk of perfluoroalkyl substances … 2.3 Risk assessment Exposure levels to PFOS and PFOA from fish were estimated by daily intake doses (ID, ng/kg/day): ID = C × R / BW Where: C is PFOS or PFOA concentration in fish (ng/g, w/w), R is fish consumption rate (g/day), and BW is body weight (kg) According to the National Nutrition Survey in 2009 - 2010, the fish consumption rate was 59.7 g/day [10] The average body weight was 60 kg The ID values of PFOS and PFOA were directly compared with the reference dose RfD = 20 ng/kg/day by the US Environmental Protection Agency (US EPA) RESULTS AND DISCUSSION 3.1 Concentrations of PFOS and PFOA in Vietnamese fish PFOS and PFOA have been detected in Vietnamese fish samples, suggesting their widespread occurrence in the environment of this country PFOS and PFOA concentrations in fish samples were presented in Table Table Concentrations of PFOS and PFOA (mean, ng/g w/w) in Vietnamese fish Species Location (year) PFOS PFOA Reference (sample size) Bighead carp West and Yen So Lake 0.092 0.033 This study (n = 6) (2016) Common carp West and Yen So Lake 0.27 0.030 This study (n = 6) (2016) Rohu (n = 6) West and Yen So Lake 0.079 0.12 This study (2016) Tilapia (n = 6) West and Yen So Lake 0.040 0.048 This study (2016) Snakehead (n = 4) Bac Ninh, Hung Yen 0.13 < 0.070 [7] (2007) Tilapia (n = 10) Da Rang River (2013 - 15) 0.020 < 0.20 [8] Snakehead (n = 3) Dong Nai River (2013 - 15) 0.16 < 0.20 [8] Dusky sleeper Dong Nai River (2013 -15) 0.050 < 0.20 [8] (n = 3) Shark catfish Me Kong River (2013 -15) < 0.080 0.20 [8] (n = 10) Flying barb (n = 5) Me Kong River (2013 - 15) < 0.080 < 0.20 [8] In the fish samples collected from Hanoi lakes, PFOS and PFOA concentrations ranged from < 0.030 to 0.48 (mean 0.12) ng/g and from < 0.010 to 0.19 (mean 0.058) ng/g, respectively PFOS concentrations in common carp (mean 0.27; range < 0.030 - 0.48 ng/g) were somewhat higher than those measured in other species (mean 0.12; range 0.067 - 0.19 ng/g) Meanwhile, concentrations of PFOA in rohu (mean 0.037; range 0.067 - 0.19 ng/g) Vietnam Journal of Food Control - vol 5, no 4, 2022 661 Tran Thi Lieu, Hoang Quoc Anh, Nguyen Thi Anh Huong, … Le Huu Tuyen were generally higher than in the remaining samples (mean 0.037; range < 0.010 - 0.15 ng/g) However, the difference in PFOS and PFOA levels between species and between lakes was not statistically significant due to large variation and small sample size PFOS and PFOA concentrations in fish samples from Hanoi lakes were comparable with those found in some locations in northern Vietnam like Bac Ninh and Hung Yen Provinces (PFOS < 0.10 - 0.30 ng/g; PFOA < 0.070 ng/g) [7], and rivers in central and southern Vietnam (PFOS < 0.080 0.16 ng/g; PFOA < 0.20 - 0.20 ng/g) [8] PFOS and PFOA levels in Vietnamese fish were generally lower than concentrations reported for some fish from other locations in China [11, 14], South Korea [12], and the US [13] 3.2 PFOS and PFOA daily intake doses via fish consumption Based on available data on fish concentrations of PFOS and PFOA (levels